An airbag device is disclosed in Japanese Patent Application Laid-Open Publication No. 2004-276680 (JP 2004-276680 A), which airbag device is provided with an airbag and a leather-upholstered airbag cover in which leather is used, the airbag cover being provided in such a manner as to cover the folded airbag. The leather-upholstered airbag cover is formed by applying leather to a resin cover body. A weakened part having reduced tensile strength is formed on the back surface of the leather. The weakened part is comprised of numerous incisions. The weakened part causes the leather to smoothly break when the cover body is ruptured.
However, it is a complex matter to manage leathers having different thicknesses, strengths, and other characteristics in order to enhance the ability of the airbag cover to deploy in the leather-upholstered airbag cover described above. In other words, the thickness of the leather must be 0.6 mm, and the incisions must be provided at a pitch of 4 mm in order to form the weakened part, and there is a risk of increased resistance to breakage of the weakened part when the parameters of 0.6 mm and 4 mm are exceeded.